Training Guide: Programming in HTML5 with JavaScript and CSS3 Ebook

Lesson 2: Working with web services CHAPTER 8 367

In this example, a math_service folder is created under the node_samples folder, and the

following package.json file is created.

{

"name": "math_service",

"version": "0.0.0",

"description": "A simple Web service",

"main": "index.js",

"scripts": {

"test": "echo \"Error: no test specified\" && exit 1"

},

"repository": "",

"author": "Glenn Johnson",

"license": "BSD",

"private": true,

"dependencies": {

"formidable": "1.x",

"express": "3.0.0",

"math_example": "0.x"

}

}

In this example, there are three dependencies. After you create this file and save it, you

can open a command prompt window, navigate to the math_service folder, and execute the

following command to install the dependencies from npm.

npm install

After the installation completes, you can use these packages. In the math_service folder,

create an app.js file and add references to these packages as follows.

var express = require('express');

var app = express();

var formidable = require('formidable');

var math = require('math_example');

After setting up the package references, create a public folder under the math_service

folder and use the app object to mount the public folder as the root of the website. The pub-

lic folder will house webpages. The code should look like the following.

app.use(express.static(__dirname + '/public'));

In this example, the operations will be part of the URL, so the addition operation is created

by adding the following code.

app.get('/addition', function (request, response) {

var x = Number(request.query.x),

y = Number(request.query.y),

result = math.addition(x, y);

response.writeHead(200, { 'Content-Type': 'application/json' });

response.end('{ "result": ' + result + '}');

console.log('Handled addition request for x=' + x + ' : y=' + y);

});